Chair spring construction



Dec. 5, 1967 J. J. BOND 3,356,358

CHAIR SPRING CONSTRUCTION Filed Feb. 14, 1966 2 Sheets-Sheet l m 52 Q/22 W275 N ,z/ H 2,; $5 20 lNVE/VTOF (/omv J, 504/0 Arm/PIE) CHAIR SPRINGCONSTRUCTION Filed Feb. 14, 1966 2 Sheets-Sheet f;

lA/VE/V/Uf day/v J Eon/0 fla W Aria/FIVE) United rates Ratent 3,356,358CHAIR SPRKNG CONSTRUCTION John J. Bond, Milwaukee, Wis., assignor toNo-Sag Spring Company, Detroit, Mich, a corporation of Delaware FiledFeb. 14, 1966, Ser. No. 527,169 9 Claims. (Ci. 2671tl2) This inventionrelates generally to an improved chair spring, and more particularly toan improved spring that is especially adapted for use in the seat of achair.

Seat springs having a variety of characteristics must be available tofurniture manufacturers to accommodate the different types of chairsthat are available on the market for the purpose of pleasing theindividual purchaser of these chairs. It had been the practice to relychiefly upon coil springs for a seat spring assembly in which thecharacteristics of the spring assembly are varied by utilizing coilsprings of different strengths and lengths. Spring assemblies of thistype perform excellently but are expensive to manufacture and requirethe manufacturer to carry a large inventory of different types ofindividual coil springs.

In an effort to reduce the cost of seat springs, the use of sinuoussprings in seat spring assemblies has become prevalent. Sinuous springassemblies are less expensive than coil spring assemblies and they doprovide satisfactory performance in some applications. However, they donot produce as comfortable a seat as coil springs do and it is not asconvenient for the manufacturer to vary their characteristics toaccommodate the difierent types of seats. Accordingly, quality chairsstill use coil spring assemblies in their seats to provide the bestperformance.

It is therefore a general object of the present invention to provide animproved spring assembly that is especially adapted to be used in seats.

It is another object of the present invention to provide a springassembly having characteristics which closely resemble thecharacteristics of a coil spring assembly but which is appreciably lessexpensive to produce.

Another object is to construct the spring in units, which may beemployed in any desired multiple to produce the desired width of thespring assembly.

Another object is to provide a spring construction in which thecharacteristics of the spring may be adjusted by changing variouslengths of one or more of the spring elements while utilizing the samegauge wire.

Another object is to provide an improved spring construction that may beformed by simple bending of the spring wire as opposed to coiling thewire or forming it into a sinuous configuration.

A further object is to provide an improved furniture spring of simpleand inexpensive but sturdy construction, which is eiiicient inoperation.

According to this invention the improved furniture spring constructionis formed in units that are employed in multiples. The quantity of unitsutilized depends upon the required width of the entire spring assembly.The several units are coupled to each other by front and rear edge Wiresfor mutual cooperation to form a spring assembly.

Each of the spring units comprises a pair of inclined front armsextending upwardly from the front of the furniture frame and toward therear of the seat in parallel relationship. A pair of similar inclinedrear arms extend upwardly and rearwardly from the rear of the furnitureframe in parallel relationship. One of the front arms is coupled to' itscooperating rear arm by a horizontal support bar while the other frontarm is coupled to its cooperating rear arm by a second horizontalsupport bar. The front'and rear arms are formed of spring wire to renderthem yieldable so that a weight on top of the spring unit will causethem to move downwardly to produce a concomitant downward movement ofthe horizontal support bars which carry the seat padding. The two frontarms, the two rear arms and the two horizontal support bars may beformed by the simples bending of a single strand of spring wire.However, since the greatest load is applied to the rear arms, areinforcing spring is connected thereto for the purpose of absorbing aportion of the load to relieve the rear arms of excess strains.

A Wire tie loop, preferably of rectangular configuration, is connectedto the two horizontal support bars for tieing them together to preventtheir lateral displacement relative to each other. The wire loop extendsforwardly of the two horizontal support bars to serve as a support forthe front portion of the seat padding and upholstery.

The several spring units are tied together by a front edge wire and aback edge wire. The front edge wire is clipped to the front edges of theseveral tie loops of the several units. In like manner, the back edgewire is clipped to the rear edges of the several tie loops of the springunits. Thus, each of the tie loops connects the two horizontal bars ofeach spring unit together, while the front and back edge Wires connectthe several spring units together to prevent their lateral displacementrelative to each other and to couple them for cooperative operation.

The foregoing and other objects of the invention, which will become morefully apparent from the following detailed description, may be achievedby means of the apparatus described in connection with the accompanyingdrawings in which:

FIGURE 1 is a plan view of a seat spring assembly incorporating thefeatures of the present invention;

FIGURE 2 is a side elevational view of the spring assembly illustratedin FIGURE 1; and

FIGURE 3 is fragmentary perspective view depicting a portion of thespring assembly shown in FIGURE 1.

Reference is now made more particularly to the drawings which illustratea seat spring assembly incorporating the features of the presentinvention. The spring is shown mounted on a wood frame generallyidentified by the reference numeral 10 and comprising a pair of sideplates 11 and 12 which are connected by a front crossbar 13 and a rearcrossbar 14 as clearly illustrated in FIG. 1. The spring assemblycomprises a plurality of spring units 15 mounted on the wood frame 10 inmutually cooperating relationship to form a spring assembly fora seat.

Each of the spring units 15 is of identical construction so that it willonly be necessary to describe one of them. Moreover, identical parts inthe several spring units will be identified by identical referencenumerals in the drawings. Each of the spring units 15 includes a pair offront arms 19 and 20. A short leg 23 extends from the arm 19 and isjoined thereto by a sharp angle so that it forms an angle with the arm19. In like manner, a short leg 24 extends from the arm 20 so that theleg 24 and the arm 20 form an angle. The short legs 23 and 24 areconnected to each other by a tie bar 21 which is rotatably supported inthe bore of a tubular portion 18 of a bracket 22.

The back portion of the spring unit 15 includes a pair of rear arms 28and 29 that extend upwardly and rearwardly of the rear crossbar 14 ofthe frame 10. The arm 28 terminates in a U shaped portion 30 whichextends through the bore of a tubular section 31 of a bracket 32 withthe crossbar of the U shaped portion 30 being rotatably supported in thetubular section 31. In like manner, the rear arm 29 terminates in a Ushaped portion 35 and the crossbar of the U shaped portion beingrotatably supported in the bore of a tubular section 36 of the bracket32. Since the U shaped portions 30 and 35 are rotatably supported by thebracket 32, the rear arms 28 and 29 can pivot relative to the bracket32. The U shaped portions 30 and 35 extend upwardly from the rearcrossbar 14 and the rear arms 28 and 29 extend rearwardly at an angle tothe U shaped portions 39 and 35. However,

in addition to being pivotable relative to the bracket 32, the rear arms28 and 29 are yieldable relative to the U shaped portions 30 and 35 andmove downwardly relative thereto when a load is applied to them from thetop.

The front arms 19 and 20 cooperate with the rear arms 28 and 29 toprovide a resilience which contributes to the comfort in the seat of thechair. To this end, the front arm 19 is connected to the rear arm 28 bya horizontal support bar 39 while an identical horizontal support bar 40connects the front arm 20 to the rear arm 29. The front arms 19 and 20and the rear arms 28 and 29 are yieldable relative to the support bars39 and 40 which further contributes to the resiliency of the spring unitwhen a load is applied upon the horizontal support bars 39 and 40.

The front arm 19 is parallel to the front arm 20 while the horizontalsupport bar 39 is parallel to the horizontal support bar 40. In likemanner, the rear arm 28 is parallel to the rear arm 29. It is thereforeapparent that the front arm 19, the horizontal support bar 39 and therear arm 28 form one side of the spring unit 15 and are all in a singleplane that is transverse to the frame 10. Similarly, the front arm 20,the horizontal support bar 40 and the rear arm 29 comprise the secondside of the spring unit 15 and are in a second plane that is parallel tothe first plane.

In order to facilitate manufacture, the portion of the spring unit 15described above is produced from a single strand of spring wire which isbent to the desired configuration in a simple bending press. Thus, thetwo U shaped portions 30 and 35, the two rear arms 28 and 29, the twohorizontal support bars 39 and 40, the two front arms 19 and 20, the twoshort legs 23 and 24 and the tie bar 21 are all formed by bending asingle strand of wire. The bending can be accomplished very rapidly andefliciently in a press with the assistance of suitable dies.

When the spring unit 15 is incorporated in the spring assembly for aseat, the greatest loads are applied to the rear arms 28 and 29 to placegreat strain on these members and their associated connecting elements.For example, a person usually drops himself onto the seat when sittingdown to apply an unusually high load to the rear portion of the springassembly. Such high load causes exceptionally large flexures between therear arms 28 and 29 and their connected elements. For example, a greatamount of fiexure would occur between the rear arms 28 and 29 and theircooperating support bars 39 and 40 respectively. As a result, thegreatest strains are applied to these members and their associatedparts.

In order to relieve these parts from such excessive strains, areinforcing coil spring 65 is connected to absorb a portion of the load.The spring has one end anchored in the bracket 22 and has its oppositeend connected to one end of a cable 66. The opposite end of the cable isconnected to a plate 67 which is fixedly secured to both of the adjacentupstanding legs of the two U shaped portions 30 and 35. This arrangementserves to connect the coil spring 65 to both rear arms 28 and 29.

The rear arms 28 and 29 are pivotable relative to the frame by reason ofthe rotatable mounting of the U shaped portions in the bracket 32. As aresult a load applied to the top of the spring assembly will cause asimultaneous pivoting movement of the arms 28 and 29 in a clockwise ordownward direction as viewed in FIG- URE 2. Such downward movement willcause a fiexure at the juncture of the horizontal support bars 39 and 40with the rear arms 28 and 29 respectively. The coil spring 65 avoids anexcessive amount of such flexure by absorbing a part of the load throughits connection with the rear arms 28 and 29. Thus, as the arms 28 and 29pivot downwardly the U shaped portions 30 and 35 will pivot with theirassociated arms. Since the coil spring 65 is connected to both U shapedportions it will begin to stretch and thereby resist the downwardpivotal movement of the arms 28 and 29. As the downward pivotal movementincreases the resistance of the spring 65 increases progressively sothat it absorbs a part of the load. As a result, the flexure between thesupport bars 39 and 40 and their associated rear arms 28 and 29 isreduced at high loads.

If a positive stop were introduced to prevent such excessive flexing,the spring would bottom, resulting in uncomfortableness to the user. Thespring 65 prevents excess flexing and yet avoids the undesirablebottoming. As the load on the spring increases, the spring becomesstiflier by reason of the action of the spring 65 but the spring stillpossesses the desired resiliency. At normal loads, the spring 65 offersrelatively little resistance to the flexing of rear arms 28 and 29 withrespect to their associated parts but when a relatively high loadingoccurs, and particularly an impact load, the spring 65 produces a highresistance to excess flexing.

The two sides of the spring unit 15 are prevented from being displacedlaterally relative to each other to retain them in operatingrelationship by a wire loop generally identified by the referencenumeral 45. The wire loop 45 is of elongated rectangular configurationand includes a pair of parallel side wires 46 and 47 joined at one endby an end wire 48 and at the opposite end by an end wire 49. The wireloop 45 is also formed of a single length of wire with its ends beingjoined by a clip 50 which also embraces the horizontal support bar 39for securing the loop 45 thereto. The side wire 46 of the loop 45extends along the length of the horizontal support 39 and is disposed inengagement therewith. In like manner, the side wire 47 of the loop 45lies along the length of the horizontal support bar 40 and also engagesit. Additional clips 51 are applied to secure the wire loop 45 to thehorizontal support bars 39 and 40.

The forward portion of the wire loop 45 extends forwardly beyond theterminus of the horizontal support bars 39 and 40 so that the front end49 of the loop 45 is disposed approximately above the front edge of thecrossbar 13. This forward portion of the loop 45 serves as a support forthe front portion of the seat padding and its associated upholstery. Theforward extremity of the loop 45 is bent upwardly a slight amount toprovide a proper support to the front edge of the'seat.

Each spring unit 15 includes one of the wire loops 45 for securing thetwo sides of the spring together for cooperative action. The springassembly includes several spring units 15 to produce the desired seatwidth. In the exemplary embodiment, four spring units 15 are provided tocomplete the spring assembly for a chair seat. These four spring unitsare connected to each other by a front edge wire 55 and a back edge wire56. The front edge wire 55 extends along the upper front edge of thespring assembly and engages each of the end wires 49 of the several wireloops 45. The edge wire 55 is secured to the end wire 49 of each of theloops 45 by a clip 57. The extremities of the edge wire 55 are bentinwardly into engagement with the side wires of the end wire loops 45and are secured thereto by clips 58.

The rear edge wire 56 is similarly mounted in the spring assembly. Itextends along the upper rear edge of the spring assembly and engageseach of the end wires 48 of the several loops 45. The rear edge wire 56is attached to each of the end wires 48 by clips 59. The extremities ofthe rear edge wire 56 are bent inwardly to engage the side wires of thetwo end loops 45 and are secured thereto by clips 60. Thus, the frontedge wire 55 and the rear edge wire 56 tie the several spring units 15together so that they may mutually cooperate to produce a springassembly which is particularly well adapted to be used as a spring forseats.

The spring construction of the present invention produces the superiorcharacteristics of a coil spring but is appreciably more economical tomanufacture inasmuch as the parts of the spring may be readily formed ofspring wire and assembled together. Moreover, the characteristics of thespring assembly of the present invention may be adjusted withoutchanging the gauge of the wire by simply changing the lengths of thefront arms 19 and 20 and the rear arms 28 and 29. Thus, the stiffness ofthe spring may be increased to the desired extent by the simpleexpedient of reducing the length of the rear arms 28 and 29. Of course,when a more flexible spring is desired, the length of the arms 28 and 29are increased proportionately. In certain types of seats it is desirablethat when a person sits on the seat the rear portion of the seat bedepressed to a greater extent than the forward portion of the seat. Thischaracteristic may be easily obtained with the present spring assemblyby reducing the length of the front arms 19 and 20. Thus, by merelychanging the length of the front arms 19 and 20, the desireddifferential in the depression between the front and rear portions ofthe spring assembly may be obtained. The front arms 19 and 20 may beincreased to the extent that a flat depression of the spring assemblywill be obtained wherein the front portion of the spring and the rearportion of the spring yield the same amount upon the application of aload.

From the foregoing detailed description of the construction andoperation of the illustrative embodiment of the present invention itwill become apparent that a new and improved chair spring constructionhas been provided in which the superior characteristics of a coil springare obtained with appreciably less expensive construction, and thecharacteristics of the spring may be readily adjusted to suit theparticular application by the simple expedient of changing therectilinear dimensions of specific elements of the assembly withoutchanging the gauge of the wire employed.

Although the illustrative embodiment of the present invention has beendescribed in considerable detail for the purpose of making a fulldisclosure of a practical operative arrangement by means of which theinvention may be practiced, it is to be understood that various novelfeatures of the invention may be incorporated in other arrangementswithout departing from the spirit and scope of the invention as definedin the subjoined claims.

The principles of the invention having now been fully explained inconnection with the foregoing description of embodying structure, Ihereby claim as my invention:

'1. In a furniture spring assembly mounted on a frame; a plurality offront spring arms; means mounting said front spring arms to said framefor pivotal movement relative to said frame; said plurality of frontspring arms extending :angularly from the frame and being resilientlymovable toward and away from the frame; a plurality of rear spring arms;means mounting said rear spring arms to said frame for pivotal movementrelative to said frame; said plurality of rear spring arms extendingaugularly from the frame in spaced relationship to said front springarms and being resiliently movable toward and away from the frame; saidfront and rear spring arms extending generally in a rearwardlydirection; and a plurality of support bars for receiving the load to beapplied to the spring assembly with each of said support bars having aresilient connection with one of said front arms and with one of saidrear arms for cooperative operation.

2. A spring assembly according to claim 1 including; load absorbingmeans connected to said rear spring arms to absorb portions of loadsapplied to the spring assembly for preventing excessive strains on saidrear springs.

3. A spring assembly according to claim 2; wherein said load absorbingmeans comprises a spring having one end anchored to the frame and itsother end connected to said rear arms to yieldably resist the resilientmovement of said rear arms when a load is applied to the spring assemblywith the resistance increasing as the load on the spring assemblyincreases.

4. A spring assembly according to claim 1 including; means connectingpairs of said support bars to prevent their lateral displacementrelative to each other so that the two connected support bars and theirassociated front rms and rear arms comprise a spring unit, a pluralityof said spring units being mounted on the frame to comprise a springassembly.

5. A spring assembly according to claim 4; wherein said connecting meanscomprises a wire loop formed of two side wires and two end Wires, andincluding clips attaching each of said side wires to one of said supportbars.

6. A spring assembly according to claim 5 which includes a plurality ofsaid spring units; including coupling means coupling said wire loops toeach other consecutively to unite the several spring units into a springassembly.

7. A spring assembly according to claim 6; wherein said coupling meanscomprises a front edge wire clipped to the front end wire of each ofsaid Wire loops; and a rear edge wire clipped to the rear end Wire ofeach of said wire loops.

8. A spring assembly according to claim 4 including; a front bracketmounted on the frame; means mounting said two front arms to said frontbracket for pivotal movement relative to said frame; a rear bracketmounted on the frame in spaced relationship to said front bracket; andmeans mounting said two rear arms to said rear bracket for pivotalmovement relative to said frame.

9. A spring assembly according to claim 8 including; a tie rod couplingthe two front arms of each spring unit together, said tie rod beingsupported by said front bracket for rotational movement to render saidtwo front arms pivotable relative to the frame; and said mounting meansfor said two rear arms extends from said rear arms and is rotat-ablysupported by said rear bracket to render said rear arms pivotablerelative to the frame.

References Cited UNITED STATES PATENTS 2,935,124 5/1960 Platt 267-1042,851,008 9/ 1958 Pietruszka 267-102 FOREIGN PATENTS 1,135,133 12/1956France.

386,121 1/1933 Great Britain.

0 ARTHUR L. LA POINT, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,356,358 December 5, 1967 John J. Bond It is certified that errorappears in the above identified patent and that said Letters Patent arehereby corrected as shown below:

Column 2, line 3, "simplee" should read simple Column 6, line 54,"2,851,008" should read 2,851,088

Signed and sealed this 14th day of October 1969.

ISEAL) Mtest:

Edward M. Fletcher, Jr. WILLIAM E.

\ttesting Officer Commissioner of Patents

1. IN A FURNITURE SPRING ASSEMBLY MOUNTED ON A FRAME; A PLURALITY OFFRONT SPRING ARMS; MEANS MOUNTING SAID FRONT SPRING ARMS TO SAID FRAMEFOR PIVOTAL MOVEMENT RELATIVE TO SAID FRAME; SAID PLURALITY OF FRONTSPRING ARMS EXTENDING ANGULARLY FROM THE FRAME AND BEING RESILIENTLYMOVABLE TOWARD AND AWAY FROM THE FRAME; A PLURALITY OF REAR SPRING ARMS;MEANS MOUNTING SAID REAR SPRING ARMS TO SAID FRAME FOR PIVOTAL MOVEMENTRELATIVE TO SAID FRAME; SAID PLURALITY OF REAR SPRING ARMS EXTENDINGANGULARLY FROM THE FRAME IN SPACED RELATIONSHIP TO SAID FRONT